Chemistry Test 280

Higher aldehydes are soluble in Benzene. Therefore, statement (B) is correct.

Lower Aldehydes are pungent but higher Aldehydes are fragrant. Therefore, statement (A) is incorrect.

Acetone is more polar than n-Butane and weight is comparable, so acetone has higher boiling point. Therefore, statement (C) is incorrect.

Methanal is soluble in water. Therefore, statement (D) is incorrect.

Presence of one vinyl (or ethenyl) group gives formaldehyde as one of the product in ozonolysis.

CH₂=CH- on ozonolysis will give HCHO.

• Ozonolysis is an organic reaction where the unsaturated bonds of alkenes, alkynes, or azo compounds are cleaved with ozone. 
• Alkenes and alkynes form organic compounds in which the multiple carbon–carbon bond has been replaced by a carbonyl group while azo compounds form nitrosamine.

The correct order of increasing acidic strength is Ethanol < Phenol < Acetic acid < Chloroacetic acid.

• Phenol is more acidic than ethanol because in phenol, the phenoxide ion obtained on deprotonation is stabilized by resonance which is not possible in case of ethanol.
• Also carboxylic acids are more acidic than alcohols and phenols as the carboxylate ion is stabilized by resonance. Chloroacetic acid is more acidic than acetic acid due to inductive effect of chlorine atom which stabilizes the carboxylate anion.

Baeyer's reagent (alk. KMnO₄) which is pink in colour decolourises due to the presence of unsaturation. Thus, it shows the presence of unsaturation in an organic compound.

For aldol condensation to occur, α -hydrogen atom is required for carbonyl compound.

For formaldehyde, no α -carbon and no α -hydrogen is present. Therefore, H C H O will not undergo aldol condensation.

An alpha (α) hydrogen is the hydrogen which is bonded to alpha carbon. Alpha carbon is the first carbon which is bonded to the functional group.

Benzyl chloride gives benzoic acid on oxidation.

The reaction takes place as follows:

C₆H₅CH₂Cl + 2KOH + 2[O] → C₆H₅COOK + KCl + H₂O

Toluene reacts with halogen in presence of iron(III) chloride giving ortho and para halo compounds, the reaction is electrophilic substitution reactio

The H atom or aromatic nucleus is replaced with Cl atom. The electrophile in this reaction is Cl⁺ ion obtained by the reaction of Cl₂ with AlCl₃.

Higher carboxylic acids are insoluble in water due to the increased hydrophobic interaction of the hydrocarbon part. 

• Thus, decanoic acid is highly insoluble in water, as it contains longer hydrocarbon chain.
• Decanoic acid is a ten-carbon, saturated fatty acid. It is present in palm kernel, coconut fat and in milk fat.

The above reaction is known as Etard reaction.

• The Etard Reaction is a chemical reaction that involves the direct oxidation of an aromatic or heterocyclic bound methyl group to an aldehyde using chromyl chloride. 
• When toluene is reacted with Chromyl Chloride, then a chromium complex is formed (Etard Complex) whose hydrolysis gives Benzaldehyde.

Acetic acid is obtained when acetaldehyde is oxidised with potassium dichromate and sulphuric acid.

The reaction takes place as follows: